This circuit activates a buzzer when the voltage applied to the input falls below a preset value in R1. The circuit is from an 80's American documentation.
This source was found in a 1982 American publication, but can be easily assembled using 2N2995 (PNP...
September 2017 - Panasonic Dy2L TVS diodes for network applications, security, medical equipment,...
This short-range circuit for the AM NW range was found in a 1960 Sylvania transistor manual. The...